1. Field
The present disclosure relates generally to detecting objects and, in particular, to detecting objects using radar systems. Still more particularly, the present disclosure relates to a method and apparatus for identifying an angular location of a target object using a radar system.
2. Background
Radar systems are commonly used to detect and/or track objects. For example, a radar system may be used to detect and/or track objects such as, for example, without limitation, an aircraft, an unmanned aerial vehicle, a ship, an automobile, a spacecraft, a living organism, and other still or moving objects. In particular, a radar system uses electromagnetic radiation to determine the distance and/or location of an object with respect to the radar system.
Typically, a radar system transmits pulses of electromagnetic radiation that are reflected off of objects in the path of the electromagnetic radiation. A portion of this reflected electromagnetic radiation is received at the radar system and converted into electrical signals that may be processed to detect and/or track one or more objects of interest.
A monopulse radar system is an example of one type of radar system that is commonly used for detecting and/or tracking objects that are moving. A monopulse radar system is configured to transmit electromagnetic radiation in a focused direction as a beam using beamforming techniques. The portions of reflected electromagnetic radiation received at the monopulse radar system for the multiple beams are processed separately and compared to each other. Typically, this processing and comparison are carried out during one pulse for the monopulse radar system.
Typically, a monopulse radar system generates signals that are used to identify an angular location of a target object with respect to the monopulse radar system. The angular location of a target object with respect to a monopulse radar system includes an azimuth angle and an elevation angle of the target object with respect to the monopulse radar system. In other words, the angular location of a target object with respect to a monopulse radar system may be a direction of the target object with respect to the monopulse radar system.
In some situations, a portion of the electromagnetic radiation detected by the monopulse radar system may be undesired electromagnetic radiation. Undesired electromagnetic radiation may include, for example, without limitation, electromagnetic radiation detected in response to noise, clutter, jamming sources, and other sources of undesired electromagnetic radiation.
Clutter typically refers to objects other than the target object that cause the monopulse radar system to detect undesired electromagnetic radiation. These objects may include, for example, without limitation, the ground, the sea, precipitation, animals, trees, atmospheric turbulence, buildings, radar countermeasures, and other types of objects.
Identifying the angular location of a target object when undesired electromagnetic radiation is detected at the monopulse radar system may be more difficult than desired using currently available techniques for signal processing. Further, some currently available techniques may not allow the angular location of the target object to be identified with a desired level of accuracy.
Therefore, it would be advantageous to have a method and apparatus that takes into account at least some of the issues discussed above, as well as possibly other issues.